HI,
Just wondering if there is a way to un-brick a device. I have loaded Tasmota onto a Sonoff-SV and this is now dead!
When plugging into the ftdi adapter I get the usual usb insertion tone of the USB device, then about 2 seconds later a popup appears saying USB device is not recognised.

I assume that the original bootloader is now gone as I used FlashESP8266.exe with the Tasmota firmware.

I have other eeprom programmers so may be able to recover if I can get the bootloader back on.

Often when you get reports from Windows like that, it helps to re-insert the device.
But it may also be an indication the USB port has to output too much power.
If you have USB3 ports on your computer, you may want to try one of those. USB3 may output a bit more power.

Also make sure your USB => serial adapter outputs the 3.3V
Some of the cheap ones have a setting to set to 3.3 V, but supply 5V or something inbetween.

Always check the output voltage of the adapter.

I added a 3.3V regulator to the 5V output of my (ultra cheap) USB adapter, because the built-in converter did not work. And also the added regulator may deliver up to 800 mA, which is enough for flashing ESP boards.

Also make sure your USB => serial adapter outputs the 3.3V
Some of the cheap ones have a setting to set to 3.3 V, but supply 5V or something inbetween.
Always check the output voltage of the adapter.

I added a 3.3V regulator to the 5V output of my (ultra cheap) USB adapter, because the built-in converter did not work. And also the added regulator may deliver up to 800 mA, which is enough for flashing ESP boards.

I will check ths to be sure.

I have flashed about 20 devices so far and have since flashed several devices without issue:
Sonoff Basic's, TH16, SV, Touch and 4-Channel all with the same components, bin file and hardware. This is the only one to fail.

interestingly enough, I had flashed this device with Tasmota via the Arduino IDK, before and there was no issues with this device. I just thought I would test ESPEasy method..

since Flashing, the device is not booting and is also getting hot if left plugged in to the programmer or supply voltage. Before flashing was ok, so assuming the bootloader is gone which identifies the device and allows firmware flashing which is now gone.